The present invention relates to an extrusion case for stick-shaped cosmetic, such as lipstick, which is provided with a dual-structural extruding mechanism.
An extrusion case for stick-shaped cosmetic with a dual-structural extruding mechanism is characterized in that the whole size can be miniaturized by reducing the length of the cosmetic extrusion case. Various types of extrusion cases have been proposed. For example, a extrusion case disclosed in Japanese Utility Model Publication No. H4(1992)-33069 comprises, as shown in FIG. 16, a base cylinder 4 consisting of a cylindrical housing and an inner cylinder which is fixed in the cylindrical housing, and a tip cylinder 1 which is fitted into the cylindrical housing to permit rotation relative to the base cylinder 4.
The tip cylinder 1 has an elongated aperture 11 formed in the longitudinal direction, the section of which is non-circular in shape.
A chuck 2 having a non-circular external periphery corresponding to the non-circular section of the an elongated aperture is inserted into the tip cylinder 1 to permit sliding forwards and backwards and not to permit rotation relative to the tip cylinder 1.
The base cylinder 4 is provided with a first helical grooves 5 formed in the inner surface thereof. An intermediate cylinder 6 is inserted into the base cylinder 4 to engage first projections 7 projecting from the outside surface of the intermediate cylinder 6 into the first helical grooves 5 of the base cylinder 4. The intermediate cylinder 6 is provided with second helical grooves 8 formed in the inner surface thereof. The chuck 2 is provided with a shaft portion 9 having second projections 10 projecting from the outer surface thereof. The shaft portion 9 is inserted into the intermediate cylinder 6 to engage the second projections 10 of the shaft portion 9 into the second helical grooves 8.
Further, the second projections 10 are disposed at the rear end of the shaft portion 9 of the chuck 2. The shaft portion 9 has a hemispheric projection 40 formed near the second projections 10. The intermediate cylinder 6 has an annular protrusion 41 formed around the periphery the front end thereof to close the second helical grooves 8. When the chuck 2 is inserted into the intermediate cylinder 6, the second projections 10 and the hemispheric projection 40 have to pass over the annular protrusion 41. Then, when the chuck 2 is extruded fully, the hemispheric projection 40 passes over the protrusion 41 to engage the protrusion 41 between the hemispheric projection 40 and the second projections 10, thereby securely holding the chuck 2.
However, the aforementioned prior art has problems as follows:
a) Since the second helical grooves 8 in the intermediate cylinder 6 are closed by the annular protrusion 41 at the front end thereof, the second projections 10 and the hemispheric projection 40 have to pass over the annular protrusion 41 in order to engage the second projections 10 of the shaft portion 9 of the chuck 2 in the second helical grooves 8. Therefore, the insertion of the chuck 2 into the intermediate cylinder 6 needs great forces; PA1 b) Since nothing guides the intermediate cylinder 6 during the sliding, it is not secured that the intermediate cylinder 6 slides stably; and PA1 c) Since it is not secured that the intermediate cylinder 6 slides stably as mentioned above, the chuck 2 is in the shaky condition during moving forward and the cosmetic held by the chuck 2 is thereby loaded so that there is a possibility of braking the cosmetic.